2 files changed, 49 insertions, 16 deletions

diff --git a/drivers/i2c/busses/i2c-pxa-pci.c b/drivers/i2c/busses/i2c-pxa-pci.c
index 6659d269b841..b73da6cd6f91 100644
--- a/drivers/i2c/busses/i2c-pxa-pci.c
+++ b/drivers/i2c/busses/i2c-pxa-pci.c
@@ -109,12 +109,15 @@ static int __devinit ce4100_i2c_probe(struct pci_dev *dev,
                 return -EINVAL;
         }
         sds = kzalloc(sizeof(*sds), GFP_KERNEL);
-        if (!sds)
+        if (!sds) {
+                ret = -ENOMEM;
                 goto err_mem;
+        }
 
         for (i = 0; i < ARRAY_SIZE(sds->pdev); i++) {
                 sds->pdev[i] = add_i2c_device(dev, i);
                 if (IS_ERR(sds->pdev[i])) {
+                        ret = PTR_ERR(sds->pdev[i]);
                         while (--i >= 0)
                                 platform_device_unregister(sds->pdev[i]);
                         goto err_dev_add;
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 2440b7411978..3c94c4a81a55 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -270,14 +270,30 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
 
         /* Rounds down to not include partial word at the end of buf */
         words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
-        if (words_to_transfer > tx_fifo_avail)
-                words_to_transfer = tx_fifo_avail;
 
-        i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
-
-        buf += words_to_transfer * BYTES_PER_FIFO_WORD;
-        buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
-        tx_fifo_avail -= words_to_transfer;
+        /* It's very common to have < 4 bytes, so optimize that case. */
+        if (words_to_transfer) {
+                if (words_to_transfer > tx_fifo_avail)
+                        words_to_transfer = tx_fifo_avail;
+
+                /*
+                 * Update state before writing to FIFO.  If this casues us
+                 * to finish writing all bytes (AKA buf_remaining goes to 0) we
+                 * have a potential for an interrupt (PACKET_XFER_COMPLETE is
+                 * not maskable).  We need to make sure that the isr sees
+                 * buf_remaining as 0 and doesn't call us back re-entrantly.
+                 */
+                buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
+                tx_fifo_avail -= words_to_transfer;
+                i2c_dev->msg_buf_remaining = buf_remaining;
+                i2c_dev->msg_buf = buf +
+                        words_to_transfer * BYTES_PER_FIFO_WORD;
+                barrier();
+
+                i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
+
+                buf += words_to_transfer * BYTES_PER_FIFO_WORD;
+        }
 
         /*
          * If there is a partial word at the end of buf, handle it manually to
@@ -287,14 +303,15 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
         if (tx_fifo_avail > 0 && buf_remaining > 0) {
                 BUG_ON(buf_remaining > 3);
                 memcpy(&val, buf, buf_remaining);
+
+                /* Again update before writing to FIFO to make sure isr sees. */
+                i2c_dev->msg_buf_remaining = 0;
+                i2c_dev->msg_buf = NULL;
+                barrier();
+
                 i2c_writel(i2c_dev, val, I2C_TX_FIFO);
-                buf_remaining = 0;
-                tx_fifo_avail--;
         }
 
-        BUG_ON(tx_fifo_avail > 0 && buf_remaining > 0);
-        i2c_dev->msg_buf_remaining = buf_remaining;
-        i2c_dev->msg_buf = buf;
         return 0;
 }
 
@@ -411,9 +428,10 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
                         tegra_i2c_mask_irq(i2c_dev, I2C_INT_TX_FIFO_DATA_REQ);
         }
 
-        if ((status & I2C_INT_PACKET_XFER_COMPLETE) &&
-                        !i2c_dev->msg_buf_remaining)
+        if (status & I2C_INT_PACKET_XFER_COMPLETE) {
+                BUG_ON(i2c_dev->msg_buf_remaining);
                 complete(&i2c_dev->msg_complete);
+        }
 
         i2c_writel(i2c_dev, status, I2C_INT_STATUS);
         if (i2c_dev->is_dvc)
@@ -531,7 +549,7 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 
 static u32 tegra_i2c_func(struct i2c_adapter *adap)
 {
-        return I2C_FUNC_I2C;
+        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }
 
 static const struct i2c_algorithm tegra_i2c_algo = {
@@ -719,6 +737,17 @@ static int tegra_i2c_resume(struct platform_device *pdev)
 }
 #endif
 
+#if defined(CONFIG_OF)
+/* Match table for of_platform binding */
+static const struct of_device_id tegra_i2c_of_match[] __devinitconst = {
+        { .compatible = "nvidia,tegra20-i2c", },
+        {},
+};
+MODULE_DEVICE_TABLE(of, tegra_i2c_of_match);
+#else
+#define tegra_i2c_of_match NULL
+#endif
+
 static struct platform_driver tegra_i2c_driver = {
         .probe   = tegra_i2c_probe,
         .remove  = tegra_i2c_remove,
@@ -729,6 +758,7 @@ static struct platform_driver tegra_i2c_driver = {
         .driver  = {
                 .name  = "tegra-i2c",
                 .owner = THIS_MODULE,
+                .of_match_table = tegra_i2c_of_match,
         },
 };